Behind Locked Doors
by My Vantilene
Summary: Dipper's solved mysteries far greater than the challenge a mere 16-year-old could present. Digging up dirt on Robbie would be a piece of cake. Wendy x Dipper, Wendy x Robbie.
1. Chapter 1

_I have been trying to write this for days, but I could only stare at the blank Word Document as "I thought you two were off playing spin the bottle with Soos." replayed in my head over and over again and I knew I could never top a joke that great. Then I decided to completely abandon that idea and, boom, this one came._

* * *

Wendy hadn't really noticed anything dubious about Robbie. Of course, she knew facts that should've made her dubious, but the suspicion just wasn't present in her mind. Like how he never picked up when she called his home phone, and how a couple hours after she did, she would receive a text message from his cellphone cussing her out, giving her the "last" warning to never use that number again. Like when it came time to gather the crew in Thompson's van, he was always picked up from different locations around town, no one ever knew where he lived. There were plenty of odd things Wendy had noticed over the years, but she had ignored jumping to any conclusions or even rising suspicion against him because he was her friend and she trusted him.

"Wendy?"

"Hmm?" she bobbed her head up from checking yet another angry text message, just to take in the sight of two green-faced twelve-year-old's and a brave, unaffected Soos.

"I chose you, dude." Soos explained, "Truth or dare?"

"Oh, um. Truth?"

"Who ya texting?" he wiggled his eyebrows in a way that would've look suggestive on anyone else, but only succeeded in eliciting a light laugh from Dipper and Mabel. Wendy giggled a bit to hide her blush.

"Well, I haven't been doing much of the texting. See, I called Robbie's house and now I've got an inbox full of —" she stopped herself from using other words when she remembered the twins, "um, an inbox full of not-so-nice messages."

"Why?"

"Uh-uh, Soos. That was one truth. Now it's my turn. Dipper." She sat up in her chair and crossed her legs, setting the phone onto the counter, "Truth or Dare?" she wiggled her eyebrows in a way that was efficiently suggestive.

"Dare."

"Can you do that thing, uh, what was it called, the lamby—"

"Truth!" he shrieked, trying to spring to his feet in enthusiasm, but instead his foot snagged on the peg of his stool and he went down with it. Pushing the stool off of himself, he added, "I pick truth."

She smiled smugly, "Alright, just keep your pants on while I think of a good one." She scratched her chin contemplatively, "Got any bright ideas, Mabel?"

"Oooh! Ooooh! Ask him about that time in 5th grade when—"

"Hey, is that Grunkle Stan's car?" Dipper interrupted, pointing wildly out the window.

"What?"

"Where?"

The trio rushed to the window and pulled up the blinds, eying the nighttime woodland scenery with slow realization. The rocky, weed-littered driveway was completely void of any cars.

"Grunkle Stan's not out there, is he?"

"Nope. There, I answered with truth. That counts."

"What, that's lame."

"No, no," Soos patted Wendy's back as they made their way back to the seats, "He got us."

"Tch. Whatever. Just pick your poison and get it over with already."

"Why, do you — do you have any other plans for the, uh, the night that we're keeping your from?"

"If I did, do you think I'd still be here?" she deadpanned, "It's almost eleven, the Mystery Shack closed three hours ago, where is that cheapskate?"

"Who knows, probably avoiding —"

Right on cue, the answering machine piped up again, "Hey, Stan, it's Lazy Susan. From the diner? _Wink_. _**Wink**_. Just calling to say hey again. You're not around your phone a lot, are you? That shack of yours must be busier than I —" Wendy sat up with a huff and yanked the answering machine from its plug. Dipper and Mabel gave her varying glances of appreciation, and Soos whistled.

"It was driving me insane." She elaborated as an attempt at justification, as if everyone there wasn't eternally grateful to have Lazy Susan's voice out of their heads.

"Alright. I choose Wendy again. Truth or dare?"

"Truth. I don't want to get stuck with another put-the-age-old-thing-behind-the-radiator-in-your-mouth dare again." She elucidated, eyes never leaving Soos's foolishly proud face.

"What's with you and this Robbie guy?" Dipper asked, hoping to sound casually inquisitive, like his curiosity only happened to be piqued because of Soos's question, and definitely not because it's what he stayed awake wondering for half the night. But he was never sure if he had succeeded or failed in doing so.

"Wow, that's kind of a vague question. We've known each other since birth, practically. Small town, dork, that's how it works. I don't know what else to tell you. He's pretty into music, so sometimes he'll take us to concerts and stuff and he _has_ written a couple songs for me. He's got a bit of a temper, but you get used to it. There was that one time when my date came down with a serious cold the night before the Homecoming dance, and Robbie offered to take me instead. It was a pretty fun night. So, my turn. Mabel, I pick you. Truth or dare?"

Mabel chimed in a discordantly saccharine tone her choice, but Dipper never really heard any coherent words. It seemed like his ears were filled with white, hot noise. He crossed his arms and squinted as his sister took something from behind the radiator and held it out for her tongue to taste.

There were plenty of odd things Wendy had noticed about Robbie over the years, but she had ignored jumping to any conclusions or even rising suspicion against him because he was her friend and she trusted him.

But Robbie was in no way Dipper's friend, so there was nothing holding him back from digging as deep as the secrets and lies went.


	2. Chapter 2

_YES YES IT'S FINALLY DONE! Also, for those of you who don't know, updates come much faster if you guys would kindly check out my writing-specific tumblr, myvantilene. Kay? Great, thanks._

* * *

Once Grunkle Stan had arrived back at the shack, he rebuked his two "freeloading" employees for breaking the dingy radiator over a dare, as well as the two underage workers for not being in bed by three. After all, the little squirts had a big day of work ahead of them to pay for the smoking hunk of metal. They were just lucky it hadn't set off the fire alarm, or they would've had more to cover than just the comparably minute price of an appliance. The last thing he needed was for the police to show up. He's seen colder, but the county jail is still considerably cold.

"You know there's still no batteries in the remote…" Mabel commented after Soos and Wendy had vacated the seedy tourist trap, and Stan was pushing the twins up the stairs, to their beds in the attic.

"Oh." He stopped guiding them up the creaking steps, leaving the twins lost and deserted on the wide, third step. He took one of the stools and slid it next to the peeling wall. Less-than-agilely, the deed-holder climbed the stool and retrieved the batteries from the smoke detector. After discarding the used batteries from the remote, he half-heartedly lodged the pillaged treasure from the smoke detector into the impossible slots. Getting them in there was like trying to pull a sword from a thick block of concrete, but channeling his inner Arthur, Stan managed to fit them in and when he slid the black covering over his accomplishment, the pointed end locked into place with a satisfying click. He waved the remote to a bleary-eyed Mabel.

"See? That's two birds with one stone. Now go on, get to bed before I have to sling you up there myself."

Mabel, being the more awake one of the two, nodded with a drunk, subdued smile and a wobbly laugh as she took Dipper by the hand and whisked him up the aging staircase, pushing him into his bed and jumping into her own.

Except Dipper was truly the more awake one. His eyes were closed, and he didn't react much to outside forces, but his mind was an incensed wasp nest, buzzing with the unanimity of a thousand livid battle cries, yet despite the cacophony and despite the chaos, his thoughts traveled more like experienced bees. One question was always met with an almost satiable answer, and another question to ponder. He went at it like clockwork, his brows furrowing ever so often at a gape in his knowledge. However, to an outward onlooker, he seemed caught in the throes of a horrific nightmare. If only those onlookers knew. If only they knew he was not experiencing a particularly nasty self-imposed abstraction, but leading a particularly successful investigation against a certain raven-haired guitar-playing punk.

At exactly 6 AM, he finally found the solution to his problem. He knew exactly how to bring Robbie down, and down for good. Not wanting to forget his brilliant discovery, he wrote it down in one of Mabel's vampire novels, which were conveniently resting on their bedside table.

He gave a small, tired laugh before being fully engulfed by sleep.

* * *

When he awoke, it was to his reluctance and Mabel's high-pitched full-volumed interrogation.

"Hey, Dipper! Dipper! What's this?" She tried to showcase the page he had written on, but the novel's insides fluttered like frightened doves and there was no way to tell what she was referring to. What had he wrote last night? It had been his secret to taking Robbie down, to exposing him for the creep he truly is. It must've been good.

"Why did you have to scribble all over the best part?"

"Wait, what?" He took the book and examined the page. Scrawled across the text in his own hand writing was a single word. Robbie.

"What? No!" he started flipping vigorously through the piece of supernatural fiction, looking for any traces of the red marker he used, "There has to be more!"

"There isn't. Trust me, if you had damaged another page, I would sense it."

The cry of a strangled animal rose from his throat.

"What are you kids doing up here?" Grunkle Stan asked from the threshold, his slovenly appearance almost mistaken for a hairy, North American myth in the children's eyes.

"I was getting Dipper up like you asked."

"I said get him up, not give him a heart attack. Sheesh." He waved their antics off, as a good caretaker is known to do, and descended the stairs again.

* * *

After scarfing down his breakfast at a rate that even Mabel couldn't efficiently keep up with, Dipper tried to slip past Grunkle Stan and a full day of tedious chores, hopeful that he would have the real mystery uncovered before anyone noticed he was gone.

He was half way across the Mystery Shack's clearing when a loud, booming voice rang out, "Hey, Thing 2!"

The front door slammed open, revealing an angry North American myth, and behind him, an absently beaming Mabel. Soos pulled into the clearing in his mud-splattered truck and got out. Dipper tried to make a break for it. Ditching Grunkle Stan hadn't been all that hard at the lake, he couldn't imagine it being any—

"Soos, perfect timing! Don't let the kid get away!"

The handyman executed a mock salute and bounded after the city boy. Dipper ran as fast as he could, but once he shot a glance behind him, his heart skipped nearly three beats and his lungs collapsed on him. Nothing takes a twelve-year-old's breath away better than the frightening image of Soos on the hunt. His insides were burning and desperate for air, but he never stopped running, and he had no idea why. Whatever Robbie's big secret is, it surely doesn't deserve this much effort and oh gosh, why couldn't he get that image of Soos out of his mind it was just downright _terrifying_. He saw a glimmer of hope as the clearing turned into a narrow, unpaved road, but that glimmer died, just as Dipper almost did when Soos side-tackled him to the ground.

"Sorry, dude." He apologized as he got off of the crushed boy, having made it impossible for him to run ever again.

"Eh…" he offered, the only sound his severed jaw could manage.

"But you know," he whispered as he helped him up, secured his arm around his shoulder, and together they walked towards the shack, "if it was you _and_ Mabel running off, I might've let you go."

"What?"

"Dude. Going on an adventure without Hambone?" he shakes his head for the shame, "It just isn't right."

"Not an adventure." He huffed.

"I may not look like the brightest knife in the crayon box, but it takes someone without brains to never notice that wherever you two go, something weird always happens."

"What do you think you were even going to do in those woods, boy?" Grunkle Stan asked as he limped back into the shack with Soos, "Nothing but trees out there. Nothing exciting about trees. I mean, unless you cut them down. Oh, just get to mopping already." He waved him off, heading towards the bathroom to prepare for another day of profitable tours.

"Dipper," Mabel called, "Think fast!" she threw a mop in his direction, which he caught expertly, having been versed in his sister's usual antics.

"So, what was so important you couldn't wait for Grunkle Stan's tour to start?" she asked after a few minutes spent mopping in silence.

"Eh, you know." He shrugged, hoping she would let it go. Of course, he knew she wouldn't.

"Don't think I buy that nonchalance for a second, Dipper! Were you really going to ditch me here with _Grunkle Stan_?"

"I — didn't even really have anything planned. You know I don't think as well in the morning. For all purposes, Soos woke me up."

"Uh-huh. But you did want to do something. You wrote Robbie's name in my book, don't think I've forgotten about that."

"Mabel…"

"Dipper!" she chirped.

"Sorry about your book."

"Wha — oh, yeah, you _did_ scribble on the best part. She was about to figure out he was a vampire!"

"I'll make it up to you somehow, I promise."

"Spin me a tale…!" she sang.

"Um. What?"

"Make up a vampire romance for me. I mean, it is the least you could do after ruining my copy."

"Does it have to be about vampires?"

"Werewolves work too."

"Alright. Uh. There once was a dude from Nantucket…"

* * *

After all the chores had been done, and Dipper's werewolf epic came to an unsatisfying conclusion, as Mabel was quick to point out, he finally was able to read from the yellowed, aging pages of 3. As he was delving into it's cryptic answers to questions not yet posed, he was allowed a moment to think clearly. What would he have done if Soos hadn't been there? Where was he supposed to start, if he had no idea what he was actually trying to find out about his competition? And what if there was no secret? Yeah, yeah, Gravity Falls has an ocean of mysteries and there are buried secrets wherever you step, but some of the townsfolk were as readable as Toby's newspaper. Wendy clearly isn't a homicidal telepath, or a bunch of gnomes in disguise, so why would Robbie be any different? The rest of the crew didn't seem to hold any experience with the supernatural before the incident at the convenient store.

Speak of the devil.

"Hey, Wendy, you ready for bowling?" Robbie asked, striding into the Mystery Shack. Dipper narrowed his eyes at him.

"Whoa, whoa, whoa," the redhead shook her head at Robbie and Thompson, "I told you guys about coming into the shack." She threw a wild glance toward the living room, then whispered, "What if Stan finds you guys in here?"

"Oh, relax," Robbie draped an arm around her shoulder, "That old kook won't mind if we steal you for the evening, will he? Besides, it's almost closing time, you think he's going to get any customers?"

She sidestepped him and removed his arm from her shoulder. Her eyes shot a pleading look in Dipper's direction, to which he hoped read "Get this creep away from me," and not the "Cover for me," he knew it was.

"Hey, I've already finished my chores and I've got nothing planned for tonight. I could finish your shift if you want."

"Oh, thanks, Dipper, you're the best!"

But he couldn't enjoy the compliment because Robbie, jaw giving a soft thud as it landed, was _staring_ at him. Gawking, as if he had never seen anything quite like him in his entire life. It was freaking him the heck out.

The moody teenager regained his composure, expression changing quicker than the weather in Florida.

"Yo, why don't we bring the kid?" He suggested nonchalantly, as Wendy and Thompson were halfway out the door.

"Uh…"

"Personally," Wendy admitted, "I'd love to, but we can't leave the cash register unmanned."

"He's got a sister, doesn't he?"

"Robbie, I left the car on. And _Lee inside it_. With _Nate_. You don't want my mom to ground me again, do you? That means we have to walk everywhere."

He squinted at Dipper, "Get your sister."

"Um… If you really want me to…" and with that he disappeared into the domestic section of the complex.

"I didn't think you liked Dipper." Wendy stated, astonishment evident in her twin, elevated eyebrows.

"Whaaaaat?" he gave a plastic smile, "The kid's like a little brother to me."

"Since when?"

"Well…Since always. The way he handled those ghosts, that was really cool of him. Captain Fun Times, you know." He paused a moment and thought aloud, "Those ghosts, that makes sense."

"Um, what?"

"It's not that big a deal he comes, right? You said yourself the kid's not half bad."

They gave him disbelieving looks, but the accompanying comments were cut off when Dipper emerged from the back with his twin in tow.

"…but you think you can handle it, right?"

"Dipper," she slapped his back, "Who do you think you're dealing with here? I'm Mabel, remember. Ma. Bel."

"So, uh…" Dipper stammered, when he remembered Robbie.

"Just get in the car, dweeb." Robbie remarked.

Thompson and Wendy exchanged a look.

* * *

Believe it or not, Dipper actually managed not to make a fool of himself for most of the night spent at the rickety old bowling alley. Feeling much more comfortable on his second night out with the crew, he was able to joke and laugh naturally. Of course, Wendy caught him off guard multiple times, and he can admit that he normally didn't respond in a fashion that could be described as "cool," but that was okay. You win some, you lose some. Even Robbie was being bizarrely okay with him, going as far as to ruffle his hair whenever he made a strike. His whole evening was going on famously. That probably should've been his first clue.

No, no, his first clue should've been when Robbie asked him to help him find a 10. 7 weight bowling ball when none of them were marked with decimals.

They were looking in one of the supply closets the apathetic and clearly delusional cashier had pointed them toward. Robbie slammed the door. It shut on the two of them and as the darkness settled so did Robbie's intentions on Dipper's mind. Something from inside his hood glowed an ethereal red.

"There's a reward out for your head, you know." He spoke after a moment of letting the light inside his pocket radiate against his face, the shadows dancing like finite monsters.

"But I'm not like Gideon. I could take the prize from his sweaty hands, sure, no problem. I could take the gnomes up on their offer. I could be swimming in riches your kid brain couldn't even wrap itself around. 'Cept that's not how I do things. You see this symbol on my jacket? It's not there for nothing. I do things from the heart, or not at all."

He took a glowing amulet from the inside of his pocket, letting the light throw shadows into sharp relief.

"Familiar, isn't it? You have one too. Not that you'll ever learn how to use it. It takes years of practice and concentration. That is, if you're normal, like you and me are, Dipper. Now your sister? Gideon? They'd pick it up easy. They've already got power sleeping deep inside them. But I had to work so hard to be able to use it. You know how long I've been trying to master this artifact? My whole life. I grew up clutching this stupid thing, hoping to unlock its mysteries. And what can I do with it after all these years of trying and trying? I can make it glow. That's all I can do with it. I've spent my whole life slaving over a nightlight."

"W-why are you telling me all this?"

"Isn't it obvious?"

"Now that you've told me, you have to kill me…?"

"I'm a lot of things, Dipper. But I'm not a murderer. I've told you because you have 3. I've spent my life studying a book similar to it. 1. I have the first book. Yours deals with monsters, Gideon's deals with spells—"

"Gideon has one?"

"Well, duh. He has 2. Anyway, mine deals with alchemy. The first rule of alchemy is equivalent exchange. So I gave you information. In exchange, I need 3."

"What? No! I need the information in that book for me and my sister's protection. You have no idea how much the supernatural loves to target us."

"Oh, don't I? They have always targeted me. Ever since I was born. You've been here, what? A week or two? This has been my ever-loving nightmare since day one. And you guys get off so lucky. At the end of the day, you still have your retarded sister and your crazy old man to come home to. You can talk to that whackjob about everything you've been through, and she doesn't call you crazy. You have no idea what the monsters of Gravity Falls have done to me! One even went as far as to mar— No. This is more than equivalent. I'm not saying another word until you hand over that book."

"You said 1 dealt with alchemy? What is that, prehistoric chemistry?"

"I wish, chemistry would be easier for normal people like us to use. But you know what? I said enough. I may not be able to use this thing, or transform into a large gnome monster, or build a gobblewonker from scrap metal, but trust me I can still beat your—"

Just then the door opened.


End file.
